Old Leafsprung Land Rovers

In my experience as long as they're good quality and regularly checked the little inline filters are OK. I've had one poor quality ebay one drop in half on me, I think the fuel dissolved the glue holding the thing together 

I also read somewhere of one causing running issues. When the car was initially started it would run fine for 5 mins and then cut out. It turned out that the filter was fine initially but once fuel started flowing the paper element would swell restricting the flow of fuel.